ID go with the Naish Areo if you really want a medium.
Personally, I weigh 214 and am patiently awaiting my X2 18m. Until then I get by with some takoons (don't recomend) and Airblasts.
I've found sucess switching to a wider board when the wind is questionable. For light wind I ride a TwinTip(http://www.twintip.com
) BAT 164 and a Naish 5'3" Twin.
The winder board looks kind of silly and I picked it up as an experiment in Maui. But being a bigger guy it really gets me going quick in teh unpredictable wind of the Northeast.